Gas firing system



June 24, 1930.

R. THURM GAS FIRING SYSTEM Filed May '7, 1926 4 Sheets-Sheet 1 INVENTORmam/w ram/*7 ATTORNEY-5' June 24, 1930. R, THURM 1,765,549

GAS FIRING SYSTEM Filed May 1926 4 Sheets-Sheet 2 INVENTOR RICH/4RDTHUR/4 ATTORNEYS Filed May 7, 1926 4' SheetsSheet 3 INVENTOR v RICH/M70THUR/v ATTORNEYS- Patented June 24, 1930 UNITED STATES PATEN; OFFICERICHARD TH'QRM, OF SAGINAW, MICHIGAN, ASSIGNOR TO BAKER) PENS COMPANY,OF SAGINAW, MICHIGAN, A CORPORATION OF NEW YORK GAS FIRING- SYSTEM.

Application filed May 7, 1926. Serial No. 107,345.

This invention relates'to gas firing systems and particularly to thosesystems wherein 1t is necessary to mix the fuel gas with oxygen beforesupplying it to the burners.

In heating baking ovens, drying rooms and the like, and especially inovens of the traveling tray type, in which articles are baked by beingcarried continuously through the heated chamber on an endless conveyor,a

large-number of long tubular burners are provided in the chamber. It isevident that since the fuel gas is burned inside the chamber to beheated, the atmosphere in such an oven consists of the products ofcombustion of the gas, steam and vapors from the articles being bakedand is practically free of oxygen. For this reason, a suflicientquantity of oxygen, or oxygen-containing gas such as air, must bemixed-with the fuel before combustion will take place.

It is, therefore, one object of this invention to provide gas firingsystems of .this class with an improved mixing and proportioningchamber, whereby. the proportion of fuel gas and oxygen may beaccurately predetermined.

It is a further object to provide such systems with means formaintaining the proportion of the gases at a predetermined valueirrespective of the rate of flow of the mixture.

It is often desirable to vary the intensity of heat in the oven attimes, either in different sections or in the entire oven. This isaccomplished by merely turning ofi or on certain of the individualburners, or by adjusting the flow of gas through the same. It is wellknown, however, that when any of the outlets of a fluid system areclosed, the pressure at the other outlets increases, and when any of theclosed outlets are opened, the pres- Therefore, when certain of the gasburners are turned oil, or are adjusted to diminish the flow of gas, thepressure at the other burners is increased, and when certain of theburners are turned on or are adjusted to increase the flow of gas, thepressure at the other burners is diminished. The variations in pressurethus produced at the burners causes the flame of the burners to beirregular sure at the other outlet diminishes, provided the supplypressure is steadily continued.

A more specific object of this invention is vto provide an arrangementwhereby the amount of gas supply and, therefore, the pressure in themains may be so regulated that when the pressure in the mains increases,the supply will be reduced and when the pressure decreases, the supplywill be increased.

These and other objects of the invention will become more apparent uponconsideration of the following description, taken in conjunction withthe accompanying drawings, illustrating the invention in its preferredform.

In the drawings- Figure 1 is a diagrammatic representation of a systemfor use in an oven built in accordance with this invention;

Figure 2 is a view partly in elevation and partly in section, of the gasmixing valve and controlling mechanism therefor; I

Figure 3 is a section taken on the line 3-3 of Figure 2; l v

Figure 4 is a section taken on the line 44 of Figure2; 80

Figures 5 and 6 are views similar to Figure 3, illustratingmodifications of the gas mixing valve shown in Figure 3;

Figure 7 is a plan View of a relay controlled valve;

Figure 8 is a section taken on the line 88 of Figure 7 and v Figure 9 isa section taken 'on the line 9-9 of Figure 7.

Referring to Figure 1, fuel gas (for example, ordinary illuminating gas)is compressed in a compressor 10, and is fed through pipe 12, ofsuitable cross sectional area, and containing a well known form ofpressure regulator 14 and a control valve 13, into a gas mixing valve orchamber 15. A second compressor 11 feeds an oxidizing gas such as air atsubstantially the same pressure as the fuel gas gpieferably 16-20 watercolumn pressure through pipe '16, having a control valve 17 and apressure regulator 18, into the opposite side of valve 15, so that amixture may be efiected. A check valve 47 is interposed between thevalve 15 and the control valve 17 so that, in case backfiring occurs inthe'burner tubes, the gases in the tube system or the burner side ofvalve 17, being under high pressure, will be prevented from penetratinginto the tube 16 and thus into the compressor 11 and regulator 18.

' A coupling section 22 leads from the upper side 21 of valve 15 to amain supply line 23, from which branch lines 24, 25, 26 and 27 extend,each one supplying a plurality of tubular burners 29, 31, and 35 throughmanifolds 28, 30, 32' and 34 respectively. Suitable control valves 36,37, 38 and 39 are located in the branch lines, and each burner isprovided with an individual regulating valve 40. With the gas mixingvalve 15 sup-.

plying its maximum capacity, and all of the valves 40 of the burners'fully open, as are also valves 36 to 39, inclusive, it is intended thatthe pressure in section 22' and main 23 remain constant and preferablyequal to 4-6 water column pressure.

The amount of mixture supplied to main 23 is controlled automatically inaccordance with the pressure existing in section 22 by means ofmechanism represented diagrammatically at 20 and shown more in detail inFigure 2, a pipe 41 providing the proper connection. Therefore, wheneverthe pressure falls below 46" the amount of gas supplied is increasedfandwhen the pressure increases above .4-6, the supply is decreased.

.There is also combined in mixing valve 15 (Fig. 2) both a proportioningapparatus and a quantity regulator. This mechanism comprises a mainhousing 42, whose inner surface is circular in cross section, and madeup of cylindrical sections of varying interior diameters, the widestsection 48, thereof, being at the middle where the pipe 12 and valve 47join parts 45 and 46 respectively, section 48 being equal in length tothe diameter of the opening in part 46 (Fig. 4). Lower section v 49 andshort upper section 50 are co-axial, and I their inner surfaces formpart of the same cylindrical surface. Section 50, for convenience inassembling, has a slightly larger outer diameter than section 49 and isarranged to sup-. port on its flange 52, the flange 53 of proportioningtube 43. The flange 54 of coupling section 22 rests upon the flange 53,the three flanges being rigidly secured together by means of'bolts 55.

The proportioning tube 43, preferably cylindrical in form and of uniformcross section, is arranged within the valve 15, so that it fits tightlyin the sections 49 and 50. Between this tube 43 and enlarged section 48is a space which is divided by means of parti- -tions 56 into twocompartments or chambers, one 57 connecting with the fuel gas inlet 45and the other 58, connecting with the air inlet 46. The tube 43 isprovided with a series of vertical slots 59, 60, which are preferably ofequal length but maybe of different width, the number of slots and theirwidths depending upon the amounts of the gases to be passedtherethrough, in order to attain desired com position of the mixed gas.If it is desired to mix two gases, for example, in the ratio of two toone, the port opening to the conduit containing the gas to be suppliedin the greater amounts is twice the width of the port opening to theconduit containing the gas to be supplied in thelesser amount. As anexample, if one volume of the illuminating gas used required 5.4 volumesof air for its complete combustion, one slot 59 maybe provided for thegas and 6 slots 60 for air, as shown in Figure 3, the proportion of thewidth of the, slot for gas to that of each slot for air being as 1 is to0.9.

Figure 5 shows a cross section of a mixing valve employed when usingproducer gas, which requires an equal amount of air for combustion, theinlet 61 for the gas and the inlet 46 for air having equal bores. Inthis case, an equal number of slots 65, 66 of the same width areprovided in tube 43 between the mixing valve and chambers 63 and 64formed by partitions 62.

Figure 6 discloses an arrangement wherein there is provided, in additionto the two oppositely disposed inlets for producer gas and air as inFigure 5, two'additional inlets, one 72, for natural gas, and another,70, for illuminating gas. Partitions 68 and 69 serve to form the propernumber of chambers and there are provided a sufficient number of slots74 to 77, inclusive, in the" tube 43. In this case, if one volume ofilluminating gas requires 5.4 volumes of air for combustion, one volumeof producer gas requires one volume of air and one volume of natural gasrequires eight volumes of air. Then the proportion of the widthsof theslots for illuminating gas, producer gas, natural gas and air is asfollows:

Within the slotted cylinder 43 is a piston "7 8, which is preferablycylindrical in form,

and which is adapted to be moved longituilinally Within the cylinder 43by means of a piston rod 80, whereby the various slots,or

openings are covered to a greater or less extent, depending upon thepressure in the delivery end of the valve, as will be more fullyhereafter explained. The rod 80 is fixed in the center of piston 78 to astar-shaped bracket 81. The middle part of the latter is preferablyconstructed as a cup 82, the bottom of which contains an opening for therod 80 to pass through, a screw plug 83 (Figures 1, 3 and 4) closing thetop. Thetop end of rod 80 is provided with a reinforced member 84, andthe rod is connected with a pressure bag 79 so that when the bag isdeflated, the extending member rests upon the bottom of cup 82, and,when the bag is inflated, a certain amount of play is permitted betweenmember 84 and plug 83.

The rod 80 extends. downwardly into the interior of housing 85, througha suitable stufling box 96 and may be securely fastened to a top piece92. The top piece 92 rests on a thin circular plate of resilient metal95 mounted on the uppermost leaf of the pressure bag 79. Thisarrangement acts to prevent the top leaf from rising too high when thebag is fully inflated. For this purpose, the plate 95 is concave on itsunder side, the plate having a spherical surface adapted to fit theupper leaf of the bag when the bag is fully inflated. The plates 92 and95 are secured in place on the rod 80 preferably by means of supportingplate 93 and a nut 94 threaded on the rod.

A. circular plate 97 adapted to hold Weights 98 for adjusting the actionof bag 79 is suitably flxedon rod 80, between stufling box 96 and thetop piece 92. The lowest leaf of bag 79 is tightly secured by means ofbolts 91 between the reinforced rim of the annular bracket 89, extendingfrom the sides of housing 85 and a circular plate 90. An opening 99 inplate 90 admits fluid under pressure in--' to the bag 79 from pipe 112,which is connected through pipe 111 to the air pipe 16.

Tnterposed between the pipe lines 111 and 112 is a relay valve 110(Figures7, 8 and 9) comprising two horizontal tube sections Y119 and 120of equal length and size arranged coaxially at opposite sides of avertical tube 121, in which a piston 122 slides easily up and down.Upenings 124 and 123 in the walls of the vertical tube 121 connectrespectivelyfgo the sections 120 and 119 and are covered and uncoveredby piston 122. The latter is cylindrical in form and is provided with anannular recess 129, which is wider at the bottom and tapers upwardly.This recess 129 is located at such a distance from the bottom of thepiston that with the latter in its uppermost position, the recess is inalignment with the openings 123 and 124.

In order to prevent piston 122 from being raised higher than necessary,tube 121 is closed by plug 132, provided with a projection 133, againstwhich the tapering piston 122 may abut.

Relay valve 110 rests with its base 125 upon the reinforced part 126 ofthe top of a housing 105, bolts 127 being provided to secure it inplace. Valve rod 109 integralwith piston valve 122 extends down throughan opening 128 into housing 105 and is secured to the center of adiaphragm 100 and is movable therewith. The diaphragm is tightlystretched across the broad rim of cup 103 by means of an annular ring102 and screws 101, an annular bracket 104 extending from the walls ofthe housing and serving as a support for said cup. To the center of thediaphragm are fixed two disks, one 107, on'its upper side carrying valverod 109 and the other, 108, on its lower side, to which is secured apiston rod 113, projecting into a dashpot 118, located in a Vessel 115whose upper open end is screw-threaded into an opening 114 in the lowerpart of the cup 103. Vessel 115 is provided at its left side (Figure 2)with a flanged inlet 116, connected to which is a pipe line 41 having acontrol valve 117 and leading to tube section 22. Variations in pressurein section 22 are thereby conveyed to diaphragm 100 which, in respondingthereto, causes the opening or closing of valve 110, thereby congrhllizng the admission of compressed air into T t should be noted that tube22 might be connected directly to pressure bag 79 as shown in Figure 1,but for practical reasons it has been found more satisfactory to employcompressed air to inflate bag 79, the variations of pressure existing intube 22, to which valve 44' must necessarily respond being very small,often less than of an inch water column pressure.

The operation of this mechanism is as follows:

The pressure desired to be maintained under normal conditions in tube 22is predetermined at any value by means of removable weights 130 whichrest on support 131 secured to rod 109. The number and size of theseweights depend upon the pressure desired to be maintained on theunderside of diaphragm 100, which pressure in turn depends upon thepressure in tube 22. Enough weight 130 must be supplied to holddiaphragm 100 against the normal pressure and in such a position thatvalve 110 is normally in its fully closed position. i

As long as the pressure in the mains and, therefore, in tube 22 and onthe diaphragm 100 remains normal, valve 110 will continue in its fullyclosed position.

As soon, however, as the pressure in the mains rises because oftheshutting down of some of the burners or for any other reasons, thepressure in tube 22 will also increase. This increase in pressure willbe transmitted through pipe 41 into vessel 115 and thence "pressure bagwill therefore gradually expand upwardly, carrying with it rod 80 andvalve 78, thereby partially closlng ports 59 ,and

to an extent depending upon the distance the valve is raised. Thequantity of gases admitted to chamber 15 will be diminished and as aresult the supply of mixture to the mains and to the burners willdecrease. The pressure in tube 22 and on the under side of diaphragm 100will thereupon drop to its normal a predetermined value whereupon valvepiston 122 will close ports 123 and 124, cutting off the supply of airto bag 79. The latter will then gradually exhaust either through pinhole134 in the bottom thereof or back through pipe 112 through the upperpart of port 124 and out through atmospheric vent 136 in tube 121.

The top of piston 122 is tapered, so that when the piston is in itslowermost position, the rim of the cylindrical part of the piston isslightly lower than the top of port 124. The bottom of the latter portis level with that of port 123, while the top port 124 is considerablyhigher than that of part 123, Which preferably is ashigh as recess 129when the piston is in its fully raised position.

As bag 79 exhausts, valve 7 8 moves downwardly to open to a greaterextent ports 59 and 60. As soon as the supply of gases to the mixingchamber is thus increased, the pressure in tube 22 again rises slightlyand valve 110 will open slightly, admitting enough compressed air intobag 79 to raise valve 7 8 once more. This cycle of operation isrepeated, the movements of valves 110 and 78 becoming less and less,until the point is reached at which an amount of compressed air enterspressure bag 79 just sufficient to maintain the valve 78 in such aposition that the supply of fuel gas and air to the mixing chamber isequal to that consumed by the burners, while the pressure in the main 22remains substantially normal. In a corresponding manner, if one or moreof the burners which was turned off is again turned on, therebytemporarily diminishing the pressure in the tube section 22, the valve 78 will be automatically adjusted to increase the supply of gas and airto the mixing chamber, thereby restoring the pressure in said chamber tonormal. Thus the valve 'Z8 is automatically adjusted in accordance withthe pressure in the tube section 22 to supply just the amount of gas andair required by the burners.

It is to be understood that various changes and modifications may bemade in details and general arrangement of the apparatus withoutdeparting from the spirit or scope of the invention as defined in theclaims.

What is claimed as new is:

1. In a gaseous fuel burner system, a gas supply line, an air supplyline, a chamber wherein said gas and air are mixed to form a combustiblefuel mixture, and a pressureoperated valve arranged to control theadmission of gas and air to said mixing chamber,

means actuated by the pressure in one of the supply lines for operatingthe valve, and means actuated by the pressure of the fuel mixture forcontrolling the valve.

2. In a gas burner system, in combination, a mixing chamber,a fuelsupply main leading therefrom toa plurality of consuming units, separatepipes to admit fuel gas and air under pressure to said anixing chamber,means having communication with, and operated by the pressure in,one ofsaid pipes for regulating the volume of fuel gas and air admitted to themixing chamber, and means having communication with and operated by thepressure in the fuel supply main for controlling the operation of thelast mentioned means. w a 3. In a gas burner system, in combination, amixing chamber, a fuel supply main leading therefrom to a plurality ofconsuming units, separate pipes to admit fuel gas and air into saidchamber under pressure, the

mixture being led from the chamber into the fuel supply main, and meansfor continuously varying the volume of fuel gas and air admitted intosaid chamber in proportion to the rate of consumption of said consumingunits,

said means being operated by the pressure.

present in one of the separate pipes leading to the mixing chamber, andcontrolled by the pressure in the fuel Supply main leading to theconsuming units.

4:. ln a gas burner system, a mixing chamber, means for supplying fuelgas under pressure to said mixing chamber, means for supplying air underpressure to said mixing chamber, a fuel mixture main leading from saidmixing chamber, a valve for controlling the passage of fuel gas and airto the mixing chamber, means having communication with the air supplyingmeans and operated by the pressure therein for operating said valve, andmeans having communication with the fuel mixture main and operated bythe pressure therein for controlling the operation of the valveoperating means.

5. In a gas firing system for ovens, in combination a plurality ofburners located within the oven and adapted to burn a mixture of fuelgas and air in their correct proportion for a complete combustion of thefuel gas, pipes supplying the said mixture under pressure to the saidburners, a mixing chamber connected with the said supply pipes andhaving two separate inlets, one for the fuel gas and one for the air, aproportioning tube fixed in the said mixing chamber and so arranged thatthe fuel gas and air enter the latter in the correct proportion, a tubevalve slidably mounted in said proportioning tube for varyingcontinuously, during its movement, the quantities of fuel gas and airadmitted through the latter, and means adaptsaid supply pipes tomaintain this, pressure substantially constant during the operation ofthe oven.

6. In a gas firing system for ovens, in combination a plurality ofburners located within the-oven and adapted to burn a mixture of fuelgas and air in their correct proportion for the complete combustion ofthe fuel gas, a mixing chamber for these gases, two separate inletsprovided in said mixing chamber, one for the fuel gas and one for theair, means for supplying gas and air to said chamber under substantiallyequal and constant pressures, proportioning means arranged in saidmixing chamber and so constructed that the fuel gas and air enter thelatter in the correct proportion, pipes connected to the said mixingchamber and supplying the said burners with the mixture of fuel gas andair, and means automatically regulating the quantities of fuel gas andair admitted to said mixing chamber under control of the pressure oftheir mixture in the said pipes supplying the said burners to maintainthis pressure substantially constant durin the operation of the oven.

In a gas firing system for ovens, in combination a plurality of burnersadapted to burn a mixture of fuel gas and air in their correctproportion for the complete combustion of the fuel gas, pipes supplyingthis mixture to the said burners, a mixing chamber, from which thesesupply pipes are fed, an inlet to said mixing chamber for air, a numberof inlets for fuel gas corresponding to the differcnt'kinds of fuel gasat disposal, means for delivering the fuel gas and air at substantiallyequal constant pressures, four chambers formed by projections extendingfrom the inner surface of said mixing chamber and surrounding eachinlet, a cylindrical tube rigidly mounted in said mixing chamber withthe side walls of said four chambers fit; ting tightly thereto andhaving openings corresponding to said inlets and leading from said fourchambers to said mixing chamber, the areas of the openings for theadmission of air having the same ratios to the several areas of theopenings for the admission of the respective gases as the ratios of airto said gases required for complete combustion, and means provided insaid cylindrical tube for adjusting the quantities of air and fuel gasadmitted to the said mixing chamber Without altering their ratio to eachother:

8. In a gas firing system, the combination with a supply main forleading a mixture of fuel gas and air in proper proportion underpressure to the burners, an upright mixing chamber having an open topconnected with the said supply main and closed at its bottom, twoseparate inlets provided for the said mixing chamber, a gas mainconnected to one of said inlets and an air main connected to the secondof said inlets respectively for.

the slots being of substantially'equal lengths,

their upper and lower ends being substantially horizontally aligned, andthe relative dimensions of the sets being such that gas and air areadmitted in the required proportion, a tube valve slidingly mounted inthe said proportioning tube, an upright rod attached to said tube valve,a stuffing box in the base of said mixing chamber through which said rodpasses, a pressure bag located below said chamber and connected at itsupper end to the said rod, a pipe connee/ting the said pressure bag withthe said air main, a piston valve intersecting said pipe, a diaphragmconnected with said piston valve, a chamber over which the saiddiaphragm is stretched, a pipe connecting the said chamber with the saidsupply main, and an exhaust passage for said bag, the said parts beingconstructed and arranged so that, when thepressure in the said supplymain rises above that normally required, the pis ton valve is opened,and the said pressure bag inflated by compressed air, and, when thepressure in the said supply main drops, the piston valve is closed, andthe said pressure *bag is deflated, the air contained therein escapinggradually through the said exhaust passage.

Signed at Saginaw, county of Saginaw,

Michigan this 3rd day of May, 1926.

RICHARD THUR-M.

